Headquarters, Washington, DC Feb. 16, 2000

ONSET OF TITANIC COLLISION LIGHTS UP SUPERNOVA RING

NASA's Hubble Space Telescope is giving astronomers a

ringside seat to a never-before-seen, violent, celestial"main attraction" unfolding in a galaxy 169,000 light yearsaway. The knockout event is the collision of the fastestmoving debris from an immense stellar explosion seen inFebruary 1987 with the gas ring that circles that site.

This collision is beginning to cause the gases in the

ring to glow as they are heated to millions of degrees andcompressed by the sledgehammer blow of a 40 million mile-per-hour blast wave. In new pictures taken on February 2,Hubble's sharp view revealed four bright new knots of heatedgas at places that had been fading slowly for a decade.Under an observing program called the supernova intensivesurvey, a team of astronomers has been monitoring SN1987Awith Hubble since it was launched in 1990.

One of the first clues to the celestial fireworks came in

1997 when Hubble saw a single knot in the ring shine like abright diamond as it was first impacted by the shockwave."That was the opening jab. Now the dancing around is overand the slugfest will begin," says Robert Kirshner ofHarvard-Smithsonian Center for Astrophysics in Cambridge, MA.

"The real fireworks show is finally starting and over the

next ten years things will get spectacular. It helps thatHubble is giving us an unparalleled view," adds PeterGarnavich of the University of Notre Dame. Previous Hubble spectroscopic observations, and radio andx-ray telescopic observations of the expanding supernovashockwave all led astronomers to anticipate that the titaniccollision was only a matter of time. As far back as 1992astronomers predicted that the ring would become ablaze withlight as it absorbs the full force of the crash.

Upon seeing the new Hubble pictures, Kirshner remarked,

"It's about time. We saw that first hotspot two years ago,but I was getting nervous that we might have been mistakenabout its location. It's great to see the shock wave startto light up the ring."

The supernova, called SN 1987A, has long puzzled

astronomers. They believe the ring is made up of old gas thatwas ejected by the star 20,000 years ago, long before itexploded. The ring's presence was given away when it washeated by the intense burst of light from the 1987 explosion.The ring has been slowly fading ever since then as the gascools.

The initial supernova flash only lit up a small part of

the gas that surrounds the supernova. Much of it is stillinvisible. But the light from the crash should illuminatethis invisible matter for the first time, and help unravelthe mystery of a pair of outer rings seen around thesupernova as well.

"Now as the central ring begins to light up again, we can

see how this old material is arranged around the star. We canmap its distribution," Kirshner says. "This event gives usanother chance to see the true structure of the gas aroundthe supernova and to puzzle out how it got there."

Kirshner and colleagues plans to use Hubble to do follow-

up observations later this year to track the ongoing drama ofone of the biggest celestial collisions ever witnessed byastronomers.